In the case of mass dispatch of printed matter, such as, for example, brochures, advertising mail, invoices or bank statements, a large number of sheets have to be reliably inserted into envelopes in the shortest possible time. In this case, both the quantity and type of sheets which are to be inserted and therefore the thickness of a filled envelope and also the format of the envelope may vary between different dispatch tasks.
Devices for automatically inserting sheets into envelopes are already known from the prior art.
As an example, EP 0 504 114 B1 (Kern AG) shows a device, in which the flap of the envelope is opened by a rotating member and the envelope is fed along a feed direction of a packaging pocket by rotating members. In the process, a holding-down roller is lowered in order to somewhat open the envelope, and the packaging pocket is pivoted in the feed direction counter to the envelope, so that the envelope can be at least partially pulled onto the packaging pocket. The sheets to be inserted are then conveyed by transport elements into the packaging pocket and therefore into the envelope, and the packaging pocket is finally pivoted back in the removal direction, so that the envelope can be pulled off from the packaging pocket and conveyed on further.
The pivoting movements of the packaging pocket, which are necessary in order to move the pocket from the feed direction into the removal direction, require a certain amount of time and therefore slow down the process. Moreover, the pivotable pocket tends to “flutter” at high processing speeds, which makes its monitoring difficult and in turn limits the maximum speed and therefore the efficiency. Finally, it requires a complicated mechanical construction of the device.
Accordingly, it has been proposed in WO 2004/098905 A1 (Kern Investment Consulting Management Ltd.) to have a non-pivoting packaging pocket. The empty envelope is fed to the pocket along a feed direction and removed from the pocket along a removal direction, whereas the angles between the feed direction and the pocket, and the removal direction and the pocket are fixed but different from each other. For feeding the envelope to the pocket, a guide element with a discharge point, the guide element being convex at the discharge point, has been proposed, such as a guide plate with a vacuum device or a rotatable vacuum drum.
This proposed device is advantageous insofar as flutter of the holding device is avoided, allowing for higher processing speeds. Furthermore, using a convex guide element avoids obstruction of the removal part of the envelope. However, feeding the envelope to the holding device is a crucial step in the insertion process. Especially if high speeds shall be achieved, the known devices require careful adjustment, in particular after changing the type of processed envelopes.